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Biomedical subjects

M Locatelli

Publications and source records attributed to M Locatelli.

At least 73 records · Page 4Linked to original sources
PubMed1992

Increased right caudate nucleus size in obsessive-compulsive disorder: detection with magnetic resonance imaging.

Magnetic resonance images were used to measure the volume of the head of the caudate nucleus in 20 patients with obsessive-compulsive disorder and 16 normal control subjects. The obsessive-compulsive patients showed a significant increase in the volume of the right side of the head of the caudate nucleus compared with that of control subjects. This finding was not correlated with demographic, psychopathological, or clinical characteristics.

Adult↗
PubMed1991

A statistical approach to computerized EEG: preliminary data on control subjects and epileptic patients.

Factor Analysis represents an important method of extracting salient features from EEG data condensing functional as well as spatial informations in a few factors and so reducing redundancy of multi-channels computerized EEG data. A 16-channel computerized frequency analysis of background brain electrical activity during 3 functional conditions (eyes closed, eyes open and hyperventilation) were performed in 2 groups, 50 healthy subjects and 14 epileptic patients with generalized seizures. The differences in each frequency band between the 2 groups have been assessed by means of factor scores. Factor scores differences between control and epileptic patients have been found in theta and alpha frequency bands. These interictal EEG abnormalities were more evident in epileptic patients. This preliminary study shows the confirmatory capability of Factor Analysis and its usefulness in managing and comparing computerized EEG data.

Adult↗
PubMed1991

Tumor-associated trypsin inhibitor in induced and acquired immunodeficiency. Studies on transplanted and HIV-infected patients.

A new tumor marker, tumor-associated trypsin inhibitor (TATI), was studied in 5 patients who received successful kidney or pancreas grafts and in 30 subjects with antibodies against human immunodeficiency virus. Serum TATI concentrations were very high during the four first days after transplantation. Thereafter the serum levels decreased when the peptide was eliminated through the kidney. Consequently, the urine values were very high. The TATI concentrations of HIV positive subjects were compared with serum levels of HIV antigen and antibody, by Western blotting and determination of peripheral T-lymphocyte subpopulations. The occurrence of high concentrations of TATI in some HIV positive subjects and especially in AIDS patients, suggests that TATI could be useful in exploring physiopathological aspects of severe immunodeficiencies even if TATI levels were not correlated with the commonly used markers of the immune system status. The increased levels of TATI in immunological disorders suggests its possible use in assessing the immune response against cancer.

AIDS-Related Complex↗
PubMed1989

Renal handling of aspirin in the rat.

Aspirin (ASA), in addition to blocking platelet cyclooxygenase, thus preventing thromboxane A2 formation, can also block renal cyclooxygenase thus inhibiting the renal synthesis of vasodilatory prostaglandins (PGs) which can induce renal function deterioration. The purpose of the present study was to clarify the pharmacological basis of the inhibitory effect of ASA on renal cell cyclooxygenase in the rat. ASA was given to rats either i.v. or p.o. at doses ranging from 10 to 200 mg/kg. After both i.v. and p.o. administration ASA was rapidly detected in plasma as intact molecule. The kinetics were of a dose-dependent type with a disproportionate increase in plasma level increasing the dose. Plasma salicylic acid (SA) concentrations peaked after ASA with a precursor product relationship. ASA levels in kidney homogenates were also determined after i.v. and p.o. ASA. Whereas after i.v. administration ASA was detected in the kidney as intact molecule, no ASA was detected in the kidney after p.o. administration. SA was measurable in the kidney after both i.v. and p.o. ASA with a time course which paralleled the plasma concentrations. Results of isolated kidneys perfused with a medium containing ASA and of kidney homogenates exposed to ASA "in vitro" indicate that ASA is rapidly converted to SA by kidney tissue enzymes. After ASA hydrolysis SA accumulates in the kidney and may protect renal cyclooxygenase from the inhibitor effect of ASA.

Animals↗
PubMed1988

Influence of antacid administrations on aspirin absorption in patients with chronic renal failure on maintenance hemodialysis.

In order to investigate the possible interaction between oral aspirin and antacids in uremic patients on chronic hemodialysis, we administered to 5 uremic patients: (1) aspirin alone; (2) aluminum-magnesium hydroxide with aspirin; (3) aluminum-magnesium hydroxide followed (two hours) by aspirin; (4) calcium carbonate simultaneously with aspirin; and (5) calcium carbonate followed (two hours) by aspirin. In all the occasions, aspirin was given two hours after a standard lunch. Both antacid preparations induced comparable changes in aspirin mean peak plasma concentration (Cmax), if given simultaneously with aspirin, whereas no difference was found in other pharmacokinetic parameters. When antacids were followed (two hours) by aspirin, both Cmax and time of maximum concentration (Tmax) were significantly altered in respect to the value with aspirin alone. No changes in the time course of post aspirin serum thromboxane B2 were detected when aspirin and antacids were administered simultaneously, but the inhibition of serum thromboxane B2 was delayed when antacids were followed (two hours) by aspirin. These results indicate that the administration of antacids to uremic patients interferes with absorption of oral aspirin. This interference can be minimized if aspirin and antacids are given simultaneously.

Absorption↗
PubMed1988

Dose-effect and pharmacokinetics of estrogens given to correct bleeding time in uremia.

Conjugated estrogens have a significant and long-lasting effect in shortening bleeding time in patients with end-stage renal disease. The studies so far available indicate that repeated estrogen administrations are necessary to short bleeding time in uremia in a dose range of 95 to 325 mg. With the present study we wanted to establish whether single or repeated doses are required to induce a significant shortening of bleeding time in uremia, and the minimum cumulative dose of conjugated estrogens necessary to control bleeding time for a prolonged period of time, and to check whether the prolonged effect of estrogens on bleeding time in uremia is due to an accumulation of the drug or its metabolites in the blood. Fifteen uremics on chronic hemodialysis were studied. A pilot study carried out in five uremic patients indicated that single or repeated estrogen infusions of 0.3 mg/kg did not significantly influence bleeding time values. Therefore the subsequent studies have been carried out using daily infusion of 0.6 mg/kg. A single estrogen infusion of 0.6 mg/kg shortened bleeding time in all patients. The effect was transient and bleeding time returned to pre-infusion values within 72 hours. A 50% decrease of bleeding time or a shortening of bleeding time more than 30 to 15 minutes or less was obtained in all patients with four or five infusions (0.6 mg/kg) spaced 24 hours apart. The effect lasted for 14 days. At day 25 from the last infusion all the patients had bleeding time values comparable with the pre-infusion ones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Determination of aspirin and salicylic acid in uremic patients' plasma using reversed-phase high-performance liquid chromatography.

A simple, rapid, and sensitive method for the determination of aspirin and salicylic acid in plasma of uremic patients is reported. After extraction with hexane, aspirin (ASA) and salicylic acid (SA) were quantified by high-performance liquid chromatography (HPLC) with ultraviolet detection at 229 nm. ASA and SA concentrations and peak-height ratios were linearly related up to 20 micrograms/ml. The lower limit of sensitivity was 0.1 microgram/ml for both compounds. The average recoveries of aspirin and salicylic acid were 27 and 54%, respectively. This procedure offers better performance than do previously described methods. The sample clean-up allows quantitation of a low concentration of aspirin in uremic patients' plasma, commonly rich in interfering endogenous substances.

Aspirin↗
PubMed1983

Decline of blood and alveolar toluene concentration following two accidental human poisonings.

In two workers admitted to hospital because of a coma due to an accidental occupational exposure to a mixture of solvents, the level of toluene was respectively 823-1122 micrograms/l in the blood and 53-38 micrograms/l in the alveolar air on the second day of admission (36 h after the accidental exposure). On the fifth day, 112 h after exposure, the toluene level was 120-45 micrograms/l in the blood and 3-1 micrograms/l in the alveolar air. The urinary excretion of o-cresol, calculated as a toluene equivalent, was 0.8-0.9 mg on the second day and 1.7-1.6 mg on the third day. Urinary hippuric acid, as a toluene equivalent, was 1.7-1.4 g on the second day and 1.3-0.7 g on the third day. A half-life of between 19 and 21 h was calculated for toluene both in the blood and in the alveolar air.

Accidents, Occupational↗
PubMedDate not supplied

Color Doppler sonographic appearance of renal perforating vessels in subjects with normal and impaired renal function.

PURPOSE: The purpose of this study was to assess the prevalence and color Doppler sonographic characteristics of perforating vessels-small arteries and veins connecting the intrarenal vasculature with the capsular plexus-in healthy subjects, in hypertensive patients, and in patients with renal failure due to hypertensive nephroangiosclerosis or ischemic nephropathy. METHODS: Fifteen healthy subjects 24-34 years old, 15 healthy subjects 68-80 years old, 25 hypertensive patients, 25 patients with hypertension and chronic renal failure (15 mild, 10 severe), and 12 patients with hypertension and chronic renal failure and acute renal insufficiency due to ischemic nephropathy underwent color Doppler sonography of both kidneys. RESULTS: The few perforating arteries in healthy and hypertensive patients had various resistance indices and flow toward the capsule. Perforating veins in these patients were much more common than perforating arteries. Perforating arteries with a lower mean resistance index than the mean interlobar resistance index and flow toward the capsule were detected in 76% of kidneys in the patients with mild chronic renal failure and in 20% of those in patients with severe chronic renal failure. Only a few perforating veins were seen in patients with chronic renal failure. In 64% of the kidneys with renal artery stenosis detected in the patients with chronic renal failure complicated by acute renal insufficiency, there were perforating arteries with flow toward the kidney and a mean resistance index higher than the mean interlobar resistance index. CONCLUSIONS: Perforating vessels are recognizable using color Doppler sonography both in healthy subjects and in patients with renal failure. The prevalence and flow characteristics of perforating vessels differ between healthy subjects, patients with mild and with severe chronic renal failure, and patients with chronic renal failure complicated by acute renal insufficiency caused by renal artery stenosis.

Adult↗
PubMedDate not supplied

Genetic prediction of type 1 diabetes in a population with low frequency of HLA risk genotypes and low incidence of the disease (the DIABFIN study).

BACKGROUND: To develop a sensitive, specific screening strategy for predicting genetic risk for type 1 diabetes mellitus (T1DM) in the low-incidence continental Italian population, and to define with this tool, a cohort of high-to-moderate risk infants for an immunological follow-up study aimed at identifying environmental risk factors for T1DM. METHODS: 4855 newborns in three regions of continental Italy were screened for T1DM HLA-DRB1-DQB1 risk genotypes using a reverse line blot typing method. Risk classification was based on odds ratios (OR) found in a preliminary case-control study (356 T1DM patients, 412 controls). Screening efficiency was optimized by allele subtyping. RESULTS: Screening for well-known T1DM susceptibility genotypes [DRB1*03/*04-DQB1*0302; DRB1*03/*03; DRB1*04/*04-DQB1*0302; DRB1*04-DQB1*0302/X where X is not equal to DRB1*03, DRB1*04-DQB1*0302, DQB1*0602 or DQB1*0603] was associated with <60% sensitivity due to their low frequencies in the general Italian population. Inclusion of an additional genotype from which protective DRB1 and DQB1 alleles had been excluded [DRB1*03/X degrees where DQB1 is not equal to *0301, *0503, *0602, or *0603 and X degrees not equal DRB1*03, DRB1*04-DQB1*0302 or DRB1*07] increased screening sensitivity to 75% (specificity: 85%). Among 4855 newborns, we have found the high-risk genotype [DRB1*03/*04-DQB1*0302; estimated absolute risk (AR) 1/23] to be present in only 0.9%. The moderate-risk genotypes were found in 13.8% of newborns (estimated AR 1/177). CONCLUSIONS: Risk classification must be tailored to the characteristics of the individual population, in particular, the allelic frequencies in the background population and T1DM prevalence. We have developed a screening strategy with good levels of sensitivity that should prove effective for use throughout the Italian peninsula.

Adult↗
PubMedDate not supplied

Comparative measurements between a new logging tool and a reference instrument.

Measurements were performed on reference samples (D2O-H2O mixtures) and on highly heterogeneous rocks (Vosges sandstone) with a new logging tool designed to give access to a high spatial resolution, below 1.5 cm on the vertical scale, for a toroidal sensitive volume of 20 cm3. The results were compared to measurements obtained on a clinical magnetic resonance imaging (MRI) equipment working at the same frequency (4.3 MHz). T2 differences as high as 30% were observed for the reference samples; the shortest values were obtained with the logging tool. Porosity profiles of the rock samples were also compared to reference profiles obtained with a conventional computed tomography (CT) scanner. Both nuclear magnetic resonance (NMR) measurements underevaluate porosity by 2-4% for short T2 values (< 10 ms).

Equipment Design↗
PubMedDate not supplied

fMRI changes in the brain associated with the carotid compression test.

PURPOSE: The purpose of our investigation was to study in normal volunteers the response to a unilateral common carotid (CC) compression test using dynamic MRI sensitive to variations in blood magnetic susceptibility. METHOD: Nine volunteers, positioned in a 1.5 T MR scanner, performed a unilateral 40 to 45 s CC self-compression during the acquisition of single slice axial T2*-weighted FLASH images. RESULTS: In three subjects, the signal showed a significant 2% drop from baseline in the ipsilateral frontal temporal cortex during the compression. In another three subjects, a significant 1.5-2% signal decrease was observed in both hemispheres. In two subjects whose MR angiography showed abnormalities of the circle of Willis, the bilateral signal drop was more remarkable (3%). In one volunteer, the signal did not change. CONCLUSION: Increased deoxyhemoglobin within the brain microcirculation is the probable explanation for the signal drop. This method could be further tested in view of the widespread use of open interventional MR units.

Adult↗
PubMedDate not supplied

Excitatory pattern of gamma-interferon on natural killer cell activity in senile dementia of the Alzheimer type.

Spontaneous natural killer (NK) cell activity and NK-induced cytotoxicity after interferon-gamma (IFN-gamma) were measured in healthy elderly subjects and in patients with senile dementia of Alzheimer type (SDAT) and multi-infarct dementia (MID). Normal basal and IFN-gamma-stimulated NK cytotoxicity were found in healthy old subjects and in patients with MID. On the contrary higher NK cytotoxicity after IFN-gamma (650 IU) was demonstrated in SDAT patients than in MID and healthy subjects (p < 0.001). A significant inverse correlation between the percent increase of NK cytotoxicity after IFN-gamma and the Mini Mental State Examination score (p < 0.001) was also demonstrated in patients with SDAT. Our data might suggest a cytokine-dependent mechanism of NK activation in SDAT associated with the neuroimmune hypothesis of the disease.

Adult↗
PubMedDate not supplied

Enhanced cytotoxic response of natural killer cells to interleukin-2 in Alzheimer's disease.

Experimental data suggest an involvement of immune cellular components in the development of Alzheimer's disease (AD). Against this background, the spontaneous natural killer (NK) cell activity and the NK-induced cytotoxicity after interleukin-2 (IL-2) were studied in healthy elderly subjects and in patients with dementia of Alzheimer type (SDAT) and multi-infarct type (MID). Higher NK cytotoxicity (expressed as total lysis and percent increase) at different IL-2 concentrations (50 and 100 IU/ml/cells) was demonstrated in patients with SDAT than in healthy elderly subjects (p < 0.001) and MID patients (p < 0.001). NK cell activity of MID patients was similar to that of healthy elderly and healthy young subjects. A negative correlation between the percent increase in NK cytotoxicity after IL-2 and the Mini Mental State Examination Score was also found in SDAT patients (p < 0.01). Alterations of IL-2-mediated NK cytotoxicity may therefore support the neuroimmune hypothesis of AD.

Adult↗
PubMedDate not supplied

Renal angiomyolipoma: typical and atypical features.

Renal angiomyolipoma is an uncommon lesion, well-known to the radiologists as one of the few lesions for which a specific diagnosis can be achieved on the basis of radiological findings. It contains variable amounts of adipose tissue, smooth muscle and vessels. It usually grows as single lesion, and it can be isolated or associated with tuberous sclerosis or with the more rare lymphangioleiomyomatosis. From a radiological point of view there are typical aspects that allow a confident diagnosis, whereas more rarely there are atypical aspects that make the diagnosis more controversial. In this review the clinical, macro and microscopic morphological aspects of angiomyolipoma are presented as well as the therapeutic approaches that can be adopted in different circumstances. The most frequent and the atypical characteristics that can be appreciated with diagnostic imaging are described as well.

Angiomyolipoma↗